I have a question that came up in an assignment. The question is kind of ambiguous as to what it is asking, but here it is:"What molecules are responsible for bacteria having various colours"

For me the obvious answer would be pigment molecules. But i wasn't sure if they wanted specifics. For example green algae have Chlorophyll as their pigment molecule. But I wasn't sure if they wanted us to state a specific molecule since we would have to find the pigment molecule for several different bacteria as well as a species of fungus (Penecillium notatum).

But the problem with this part is that i don't think these bacteria are phototrophs, so why do they have pigments.

The question right afterwards asks what purposes do these bacterial pigments have ( so does that mean the previous answer IS pigments?)

A few examples of the bacteria we are looking at include : Bacillus cereus, Kocuria rhizophilia and Pseudomonas chlororaphis.

If anyone can answer this that would help out a lot!!

If you can't answer this question can you name a directory that shows all types of bacteria and other microorganisms?

Green algae are not bacteria and the question was regarding bacterial pigments, not pigments in skin.Some bacteria do produce pigments of photosynthesis but these microbes are not among the ones you mentioned.Of the bacteria offered, Kocuria rhizophilia (formerly Micrococcus luteus) yellow pigmentation is due to carotenoids the function of which here is not real obvious. Carotenoids do confer some degee of photoresistance and can function in photosynthesis. Pseudomonas chlororaphis greenish pigmentation is due to pyoverdin, a compound that helps the bug acquire iron. I'm not so familiar with B. cereus pigmentation. I've seen some vague brown, yellowish stuff and it does produce characteristic pigmentation on special media.

almost all bacteria and fungi that are exposed to the sun must produce some kind of colored or opaque protein to protect it's organelles from UV light, it might be that these pigments have no other functions in the organisms you listen than protection from the sun.